Crucible skimmer



Patented Jan. 10, 1950 UNITED STATES PATENT OFFICE 2,494,270 GRUCIBLE sKIMME-n' Virgil H. Todd. Rockford, 111-. Application August. 1 1, 1945,. SeriaLNor 6.10.297-

7 Claims. (CI. 22-83) This invention relates to the skimming ofcrucibles for pouring molten metal such as brass or bronze.

The primary object is to provide a skimmer. adapted to be movably mounted on a crucible. and actuated automatically as an incident. to. tiltingthereof so as to be maintained in. proper skim ming position in all degrees of tilt of the crucible.

A more detailed object is to provide a. skimmer of the above character which is actuated bythe buoyant force exerted thereon by the, molten metal being poured.

Another object is to support such an automatically actuated skimmer on a member which may be utilized as a. cover for the crucible to be skimmed.

Other objects and advantages of. the invention will become. apparent. from the following detailed description taken in connection with the accompanying drawing, in which Figure lis a perspective viewof the improved. skimmer.

Figs. 2 and 3 are diametricalsectional viewsof' the skimmer attached to a crucible shown in different positions.

While the invention is susceptible of various modifications and alternative constructions, I- have shown in the drawing. and will herein. describe in detail the preferred embodiment; It is to be understood, however; that I do not intend tolimit the invention by such disclosure, but-aim to cover all modifications and alternative con.- structions falling within the spirit and scope: ofv the invention as expressed in the: appended claims.

The invention is illustrated in the drawing as applied tothe ordinary crucible 5 composed of so-called crucible material which. is a mixture of graphite and clay bound together into a. compact mass. Crucibles of this character havea-pourlip 6 at. their open' ends; and are commonly used in handling molten metal, particularly brass and bronze. In pouring such metal into a mold 8, the slag. 9 which collects on the, surface must be skimmed off, this usually being done by a separate skimmer manually held in position adjacent the spout 6. To permit this, the. crucible is ordinarily left uncovered, with the result. that the zincfnmes fill the adjacent air and become oxidized-i The present invention contemplates relievingthis unhealthful condition in brass foundries and the like and in saving labor through the provision on the crucible of a skimmer i0 arranged in a novel manner so as to be. actuated automatically and always maintained in proper skimming position in all degrees of tilting of the crucible. In the form shown, the skimmer comprises the surface ll of a block l2 movably mounted on the crucible in a position to project intothe body of molten metal adjacent the spout L 6 and block the outflow of the slag 9 during pouring of the metal from the crucible.

In accordance with another aspect of the invention; the skimmer H] is mounted on a memher which forms acover for'the crucible; Herein this cover comprises a flat metal disk I 6 adapted to fit against and cover the open end of the crucible except for a peripheral opening l3 of rectangular shape positioned opposite the spout soas to'permit metal to be poured from the covered crucible while the coverremainsattached. Such attachment is e-fiected in the present instance by arms I4 fastened at spacedpoints around the periphery of the cover' and depending from the latter in. positions to fit over the crucible end and frictionally gripthe external surface thereof; The cover plate may: be lifted off from the crucible by a. handle t5 securedto the upper surface of the cover.

The skimmer HI. projects: downwardly through the pouring opening l3 adjacent the inner or closed end. thereof and its:movement to. different skimming positions is provided for bysuspending theupper-end of. the block I12: from a pivot H extending parallel to the plate #6 and: spaced. a short. distance above the, latter- As shown, the pinextenda through a boreiinthe block 12, and its opposite ends are supportedilngs l-8;upstand.- ing; from the top.- of the cover on opposite sides of; the-opening l.3-. Thus. when the crucible. is in normal upright.- position, the skimmer. block [2- hangsdownwardly and lies-adjacent thestraight inner edge Hl-of the cover opening with the lower free. end of. the block. projecting intov the crucible several inches below the. under side. of. the cover. The block is thusdisposed adjacent the inner surface of. the crucible (Fig. 2-) adjacentthe pouring spout 6.

Automatic actuation of the skimmer surface H to maintain the; same in proper skimming position: is. effected-.by a. buoyant. force derived by engagement. of the molten. metal in the crucible; with the movable skimmer. Tothis. end, the block; l2 which. carries.- the: surface: l l is. constructed; of an inert; material which. will withstand the temperatures; encountered: by dipping into the molten metal and: at the same time will heat on themolten metal". The same material 013" which the crucible walls are made is suitable for this purpose, the block [2' being approximately one inch thick in this instance.

As the crucible equipped with the improved skimmer and cover is tilted from the upright position (Fig. 2), the lower free end of the. block 12 remains against the. inner surface of the crucible until the molten metal level reaches it, thepivot LT then being, offsetv outwardly from the. block. end When the molten metal encounters the block, the latter dips through the slag layer and into the metal, remaining against the crucible wall until the buoyant force exerted vertically on the free end of the block overcomes the eccentric weight of this block end. Thereupon, the block end is buoyed upwardly away from the crucible wall as shown in Fig. 3, permitting metal to flow out beneath the block. I}

The surface ll of the latter is thus positioned to block the outflow of the slag 9 thus skimming the metal poured from the crucible. As the crucible is tilted further, the skimmer adapts itself automatically to the liquid level and thus moves relative to the crucible so as to remain in the same skimming relation with respect to the liquid level.

By utilizing the buoyancy of the skimmer in this way, the metal poured from the crucible is skimmed automatically and effectually and by a very simple construction. A substantial saving in labor is thus achieved and at the same time the crucible is covered so as to minimize the dangers resulting from the escape of the metal vapors.

By maintaining the crucible covered, oxidation of the meta] within the latter and the formation of slag on the internal side wall is kept at a minimum.

. I claim as my invention:

1. The combination of a plate for covering the open end of a crucible for containing molten metal, means on said plate adapted to interfit with the lip of the crucible and hold the plate in place when the crucible isr-"tilted, said plate hav-' ing a radially opening peripheral notch therein, a skimmer member projecting downwardly through said notch and spaced inwardly from the periphery of said plate, and means suspending said member from a pivot disposed above said plate for inward swinging under the buoyancy of the molten metal on which the free end of the member floats when the crucible is tilted to pouring position.

2. The combination of a plate for covering the open end of a crucible for containing molten metal, means on said plate adapted to interfit with the lip of the crucible and hold the plate in place when the crucible is tilted, said plate having a peripheral opening through which metal may be poured from said crucible when the latter is tilted, and a skimmer member pivotally suspended in said opening and'actuated to skimming position automatically by engagement with the molten metal flowing through said opening as the crucible is tilted.

3. The combination of a cover adapted to fit the end of a crucible and having a rectangular peripheral opening through which molten metal may be poured from the crucible, a generally rectangular member projecting through said opening and composed of a material which is lighter than molten metal such as brass, and means suspending said member from a pivot disposed above and parallel to the cover and parallel to one edge of said opening whereby to cause inward swinging of the free lower end of the member under the buoyant force exerted thereon by the molten metal being poured from said crucible when the latter is tilted.

4. The combination of a cover for a crucible adapted to contain molten metal such as brass, said cover having an opening through which molten metal may how when the crucible is tilted, a member disposed in said opening and composed of a material lighter than said metal, and means 4 on said cover supporting said member for movement of its lower end inwardly away from the crucible wall under the buoyant force of the molten metal and the maintenance of the member in skimming position in all positions of tilting of the crucible.

5. For use on a pouring crucible for containing molten brass or the like, the combination of a cover for the crucible having a peripheral opening, a member projecting through said opening to provide a skimming blade on one side of the cover, said blade being composed of material adapted to float on molten metal, and means pivotally supporting one end of said member on the other side of the cover for swinging of the member about an axis spaced from and extending parallel to the cover.

6. The combination of a plate for covering the open end of a crucible for containing molten metal, means on said plate adapted to interfit with the lip of the crucible and hold the plate in place when the crucible is tilted, said plate having a radially opening peripheral notch therein, a skimmer member projecting downwardly through said notch and spaced inwardly from the periphery of said plate, and means suspending said member from a pivot disposed above said plate for inward swinging under the buoyancy of the molten metal engaging the free end of the memher when the crucible is tilted to pouring position, the root of said notch being positioned to engage said skimmer member and limit inward pivoting thereof after partial tilting of said crucible.

7. The combination o'f-a plate for covering the open end of a crucible for containing molten metal, means on said plate adapted to interfit with the lip of the crucible and hold the plate in place when the crucible is tilted, said plate having a radially opening peripheral notch therein, a skimmer member projecting downwardly through said notch and spaced inwardly from the periphery of said plate, means suspending said member from a point parallel to and disposed above said covering plate so that the member lies along a chord of the crucible and is swingable outwardly against the inner wall thereof in the initial tilting of the crucible and then swings inwardly away from such wall under the buoyancy of the molten metal enga ing the free end of the member in the further tilting of thecr-ucible, and a stop on said cover plate engageable with said member to limit said inward swinging to a position in which the member is disposed approximately normal to the cover plate. 7

' a VIRGIL H. TODD.

REFERENCES CITED The following references are of record in the file 'of this patent:

UNITED STATES PATENTS 

